Press



Jan0 (39911934.J A. A, BYERLEiN 1,945,175

I PRESS Filed Fer@ 1, 1932 2 sheets-sheet 1 Patented Jan. 30,

PRESS 1 Arthur. A. Byerlein, Detroit, Mich., assigner to General Machin ery Com Ohio, a corporation of Delaware ration, Hamilton,

Application February l, 1932. Serial No. 590,058

' s claims. .(cl. 11s-46) This invention relates to presses, and more particularly to power presses adapted for drawing or forming sheet metal and the Ilike.

One object of the present invention is the provision of a press having a movable pressure plate which is operated in one direction against a yielding pressure cushion when the movable die comes into engagement with the work, the pressure plate having a lock independent ofthe pressure cushion for temporarily. holding it return movement during a predetermined part of a cycle of press movements. Another object of the invention is the provision of a lock of the character described having relali tively movable piston and cylinder elements in which liquid is trapped periodically, these elements having an auxiliary pressure device so that the trapped liquid may be subjected to a predetermined pressure in order to compensate for air that might have beome trapped in the liquid, or to compensate for any slight lack in lling of the `\cylinder. Other objects and advantages of the invention `vvill'be apparent from the following description,

- the appended claims, and the accompanying drawings, in which- Fig. 1 is a side elevation of a press, v shown partly in section on the line 1-1 of Fig. 2 and embodying the present invention;

Fig. 2 is a horizontal section on the line 2-2 of Fig. 1; and A Fig.- 3 is a section on the line3f3 of Fig. 2. Referring more particularly to the drawings by reference numerals, 10 designates the frame of a power press adapted for drawing or forming sheet metal or the like. In accordance with the pres-l ent invention the drawing press is of the single action type, the upper part of the press frame rotatably supporting a crank shaft 11 which is connected by cranks -12 to a movable die carry.

ing slide 13 from which the upper die 14 may be` supported. The slide 13 is guided for vertical reciprocatory movement in thc' vopposite frame sides.

The die 14 is adapted to cooperate with anlower stationary die 16 lsupported on the bolster plate 17 which is secured on the-press bed 18. A draw ring 19 surrounds the lower die 16, the draw ring cooperating with the outer portionsof the top die 14 so that the work or blank of sheet metal 21 will be gripped between these parts when the upper die descends 'in' order to hold theouter r edges of the blank under a suitable predetermined pressure preventing buckling or tearing of tend centrally across the lower sides of both cushions. The air supplied to the pressure cush- -value although movement of the air in a reverse This lock is preferably constructed independent the sheet during the Aformation of the finished article. The draw ring 19 ,is urged -upwardly in a yielding manner during the time the upper die is descending by means of a yielding pressure cushion or4 cushions provided below the bolster plate. In accordance with the present inven.- 6I tion two compressed air cushions are employed to yieldingly resist downward movements of the draw ring. Each embodies telescopically related piston and cylinder members 24 and 25 consti- 'tuting an' air chamber of variable size. The pres- 65 sure plate 23 forms the top of the cylinder 25 and is guided at opposite sides in the well or opening provided in the press bed. The lower member 24 is fixed in position on a cross plate 26. Movement iii-transmitted from the pressure plate 10 23 by means of pins 27 which project through holes in the bolster plate and which rest on the upper side of the pressure plate and support the draw ring at their upper ends.-

It will be understood that the pressure cush. ions are supplied with air under a predetermined pressure, the factory supply line being connected through a pipe 29 to the lower side each of the tlxed piston members -24. The pipe 29 may exions is regulated by a pressure regulating valve 28 which permits now into lthe cushion to maintain the air in the cushion 'up to some predetermined direction, from the pressure cushion toward the vsupply lines, is prevented by a suitable check valve.

During upward movements of the top die slide, in ordinary constructions now inl-use, the draw ring follows the upper slide and under certain conditions creates a kick back which has many objections. Means are therefore provided to temporarily hold or lock. the pressure plate against return or upward movement during a predetermined part of a cycle of operations so that the draw ring will not be pushed upwardly until after the upper slide has traveled a considerable distance away 4from the formed article.

of the pressure cushion itself and at one side of the 'pressure cushion. Two such locking devices, as shown, are provided, at opposite sides of each pressure plate, so as tohold the latter in a balanced manner until such. time in the cycle 'as the upward movement of the pressure plate is desired. These locks are of the hydraulic type as they employ oil or other liquid as the locking medium. f

The pressure plate lock is provided in the space 11o below a corner of the pressure plate. 'I'he lock rdesignated generally 31 which holds one corner of the pressure plate 23 has been shown in section in Fig. 3. 32lis.the corner of the pressure platoe, in which is fixed a rod 33 which extends suitable manner yby an adjusting nut 41, thel spring 40 engaging a valve42 which controls the flow of fluid between the chamber 38 and a pipe 44 which communicates with a reservoir 45 located at any suitable point preferably adjacent to the press and containing a quantity of oil or other suitable liquid 50 under pressure. 'I'he valve stem 46 of the valve 42 projects out through a packing member 47 and is adapted to be pushed upwardly by a lever 48 to be more fully described later. In the position of the parts shown in Fig. 3, however, the spring 40 holds the valve head against its seat, trapping the liquid in the cylinder 351and preventing upward movement of the piston 34. Whenthe valve 42 is opened, the oil or other liquid lling the cylinder 351s subjected to the pressure of the reservoir 45, and of course when the valve 42 is open the liquid can flow down through the pipe 44 into the cylinder 35 and fill the cylinder as'the piston 34 descends.A When the valve 42 is closed, with the piston 34 and the pressure plate at the lower ends of their strokes, upwardl movement of the piston 34 is prevented, since the oil is noncompressible.

It will be understood that the valve 42 is automatically controlled in timed relation to the movements of the press slide. 'Ihe lever 48 l which is engageable with the stem of valve 42 is ilxed to a shaft 53, which is operated by a lever 54, moved in turnA by a rod 55 which projects upwardly and is pivoted at its upper end to a. lever 56 provided on a suitable supporting shaft 58. On the shaft58 is a lever 59 which is operated by a rotatable cam 60. 'I'he cam 60 has a depression 61, and is fixed to the crank shaft l1 so that when the crank is in a position corresponding to the lowermost position of the slide 13, the end of the lever59 will be down in the depression 6l, as shown in Fig. 3. The construction -is preferably suchl that the lever 59 drops into the depression 61 when the crank pin is within about 10 of the bottom of its stroke, and the rise of the cam` 60 is s uch that when the crank pin is rotated to a point about one-half way up on the upward stroke of the slide, lthe lever 59 will be raised far enough to bring the lever 48 into engagement with and open the valve 42. ,This permits upward movement of the pressure plate under the influence of the pressure cushion at a time when the upper slide is about one-half wayvup on its upward stroke, the upward force exerted by the pressure cushion forcing the liquid out of the cylinder 35 through the passage 39 and past the open valve 42, returning into the reservoir. When the slide moves down yagain the liquid can flow into the cylinder 35. Thus the valve 42 is open until the lowermost position of the pressure plate is almost reached, but at that' time the valve 42 closes, the lever 59 dropping into the notch 61 at that point in the cycle of operations and forcing the lever 48 down away from `the valve 42.

The shafts 53 are duplicated at the front and rear of the machine, both being controlled at similar times by the same shaft l58. One shaft 53 serves as a, control for the valves at the rear of the press while the other serves to control the locks at -the front.

To compensate for air which may become trapped in the oil or other liquid 50, or to cornpensate for any slight lack of filling of the cylinder 35, an auxiliary pressure means is provided in order that the trapped liquid in the cylinder 35 may be subjected to a predetermined pressure, maintaining this pressure until the'desired time for release ofthe pressure plate. VThus as shown in Fig. 3, there is a passage communicating with the interior of the cylinder 35 and with a small auxiliary cylinder 66 in which an auxiliary piston or plunger 67 is reciprocably guided. The plunger 67 is the end of a piston rod on which is provided a piston 68, slidably mounted in a cylinder 69, -xed to and preferably forming a part of the casting 36. The piston 68, which may be a great many times larger in diameter than the plunger 67, is subjected to air pressure at a predetermined time in the cycle of operations. One end of the cylinder 69 has' a uid passage 70, extending to a control valve 71. The other end of the cylinder 69 is open to atmosphere through the passage 73. The valve. 71 is shown as having a rotatable plug 74 controlled by a lever 75 which is pivoted to the end of an arm 76. Arm 76 is pivotedfto a lever 77 provided on the shaft 53 so that the valve 71 will be automatically controlled at about the same time the valve 42 is operated. The valve plug 74 has a series of passages permitting the pipe to be placed in communication either`with the exhaust pipe 79 or with the air supply pipe 80 which is preferably a branch from the air supply pipe 29 of the several pressure cushions. Thus when the valve 71 is in the position shown in Fig. 3 the lower side of the piston 68 is subjected to the pressure of the compressed air in the pipe 29, the piston 68 therefore exerting a large pressure upwardly on the plunger 67 and placing the liquid 50 in the hydraulic cylinder under som'e predetermined definite pressure which will compensate for air that might be trapped in the oil and also for any slight lack of filling in the cylinder 35. The pressure of the oil 50 is maintained until such time until the valve 71 is automatically thrown over to the dotted line position, which takes place at about the same time or preferably just before the valve 42 is opened. Such movement of the valve 71 permits the exhaust of air from the space below the piston 68 out through the exhaust pipe 79, relieving the pressure o'n the oil 50. v

While the form of apparatusv herein described constitutes a preferred embodiment of the invention, it is to be understood that the invention is not limited to this precise form oi apparatus, and that 'changes may be made therein'without departing from the scope of the invention which is defined in the appended claim What is claimed is:-

1. In a press of the' character described, a prescomprising piston and cylinder elementsy relamechanical connection from one of said elements.

to said plate, the connection being'arranged to one side of said air cushion, a liquid supply connection from said'hydraulic lock, a valve controlling the flow of liquid through seid liquid supply connection, and means operated in timed relation to the press movements for operating said valve at predetermined times in a cycle ot press operations.

2. In a press of the character described, a pressure plate, an air4 cushion below said pressure plate for resisting the movement of said plate in one direction, and a lock having a liquid chamber independent of said air cushion for temporarily holding said plate against return movement during a predetermined part of a cycle of operations and comprising piston and cylinder elements' relatively movable one with respect to the other and provided below a comer of said pressure plate and at one side of said air cushion, a mechanical connection extending from a corner of the pressure plate to one of said elements externally of said air cushion, a liquid reservoir independent of said air cushion, a valve controlling the iiow of liquid from ,said yreservoir to said cylinder, and

means operated in timed relation to the press movements for operating said valve. f Y

3. In a press of the character described, a pressure plate, an air cushion arranged centrally below said plate for resisting the downward movement thereof, and 'a lock for temporarily holding said plate against return movement during a predetermined part of a cycle of operation, said lock comprising relatively movable piston and cylin-l der elements arranged below diagonally opposite corners of said plate and on opposite side of said air. cushion, mechanical connections from the movable elements to the corners of the pressure plate, and valves automatically operable in timed relation to the press movements for controlling a ow of iiuid to said cylinders.

4. In a press of the character described, a pres,

sure plate, an air cushion arranged centrally below said plate for resisting the downward movement thereof, and a lock for temporarily holding said plate against return movement during a predetermined part of a cycle of operation, said lock comprising relatively movable piston and cylinder elements arranged below diagonally opposite corners of said plate and on opposite side of said air cushion, mechanical connections from the movable elements to the corners of the pressure plate, aliquid reservoir independent of said air cushion, and valves automatically operable in timed relationto the press movements for controlling a now of liquid to said cylinders from said reservoir.

5. In -a press of the character described, a pressure plate, an air cushion for resisting the movement of said plate in one direction, and a lock for temporarily holding said plate against return movements during a predetermined part of a 'cycle of press operations, said lock comprising fixed and movable piston and cylinder elements, means connecting one of said elements to said pressure plate externally of said air cushion, a liquid reservoir independent of said air cushion, a valve controlling the flow of liquid from said reservoir to said cylinder, means operated in timed relationy to the press movements for controlling said valve, and supplementary pressure means for maintaining the liquid in said cylinder at a predetermined pressure during the time the lock is eiective.

' 6. In a press of the character described, an

operating shaft, a die slide'operated by vsaid shaft,

a pressure plate cooperating with said slide and adapted to be moved downwardly thereby, an vair cushion for resisting the downward movement of said plate, and a hydraulic lock for temporarily holding said plate against return movement and comprising iixed and movable piston and cylinder elements, a connection independent of and externally ofv said iixed element from the movable element to said plate, valve means controlled in timed relation tothe press movements for trapping liquid in the cylinder, an auxiliary piston for'subjecting the trapped liquid to pressure, an auxiliary cylinder in which said auxiliary piston operates, and means for supplying air at a predetermined pressure to one side of said' auxiliary piston at a predetermined time in the cycle of operations.

ARTHUR A. BYERLEIN. 

